In the past, it has been the usual practice to use a tube expander having a long overall tool length for performing the tube expanding operation at the baffle plates as well as the tube expanding operation at the thick wall tube plates in heat exchangers, condensers, etc. While the tube expanding operation will be effected satisfactorily if there is a sufficient space for installing the long tool, where there is provided the baffle chamber d as shown in FIG. 4 the available space L for tool installation is smaller than the overall length L of the long tool shown in FIG. 5 and consequently the installation of the tool is not possible. The occurrence of this case is relatively frequent and in such a case the tube expanding operation is effected by removing the baffle chamber and the chamber is reinstalled upon completion of the operation, thus deteriorating the efficiency of the tube expanding operation very greatly.
Where the baffle chamber has been welded making its removal impossible, after the assembling of a heat exchanger or condenser the expanded tube portions are subjected to reinforcing clamping, and in the event that there arises a need for a tube expanding operation it will be a frequent occurrence that the tube expanding operation is impossible thus making it inevitable to blank off the portion to be repaired by means of a blank or tube plug, thereby giving rise to a difficult problem of greatly decreasing the efficiency of the heat exchanger or the like.
Another disadvantage of the known tube expander is that since a propelling force must be externally imparted to the mandrel until the rollers bite into the tube, where the space is limited as mentioned previously it is not an easy matter to mount the required drive unit in position or perform the required tube expanding operation. Further, as shown in FIG. 5, the shown tube expander comprises a single mandrel 1 and a single cage 2, with the result that due to its structure the tube expander cannot be separated into the mandrel 1 and the cage 2 so as to be assembled at the time of use or operation, and after all the device inevitably results in a long tube expander.